Normal Adaptation in Pregnancy Biophysical Changes

Reproductive Organs Uterus: changes from an organ that is 4 X 6.5 X 2.5cm non pregnant to 24 X 32 X 22cm at 40 wks gestation. Enlargement results from hyperplasia & hypertropy of uterine muscle fibers and fibroelastic tissue Muscle thickens early in pregnancy and thins out later as it enlarges 2ndary to estrogen Fundus should be at level of 20wks gestation.

Reproductive Organs Cervix– changes are controlled by estrogen Endocervical cells secrete thick mucus plug to protect fetus from invading bacteria Goodell’s Sign– softening of the cx after 6wks gestation caused by  vascularization, sl. hypertrophy & hyperplasia. Cx is > friable Chadwick’s Sign– bluish coloration of cx & vagina due to  vascularization

Reproductive Organs Ovaries– early in pregnancy is a source of hormone production. Estrogen & Progesterone are produced by corpus luteum until placenta takes over in 2 nd trimester. Then they are less active

Reproductive Organs Vagina--  vascularization & epithelial hypertrophy due to estrogen gives bluish color called Chadwick’s Sign. Leukorrhea--  vaginal discharge is white to sl. gray but non-pruritic and not blood- stained. Vaginal pH– in pregnancy, the vaginal pH goes  due to lactic acid production predisposing the pregnant woman to vaginal infections especially candida albicans (yeast)

Reproductive Organs Breasts--  estrogen & progesterone levels assist in preparing breasts for lactation, allowing growth of mammary glands and breast enlargement, but oxytocin and prolactin are suppressed by high levels of E & P until time of delivery  sensitivity, tingling, tenderness are common sx early in pregnancy  pigmentation of areola is normal Colostrum may be expressed as early as 16wks gestation

Posture in pregnancy Abdominal distention gives pelvis a forward tilt  abdominal muscle tone  weight bearing These 3 factors require a realignment of spinal curvature late in pregnancy.

Posture (cont’d) Lordosis develops, walking is more difficult Hormone, Relaxin, causes hypermobility of joints leading to “waddling” gait. Relaxin helps the pelvis to be more flexible during delivery of fetus. Diastisis recti develops with enlarging uterus and may persist after delivery.

Metabolic Changes Generally, basal metabolic rate (BMR)increases throughout pregnancy with increasing needs of the fetus  by 15 – 20% by term  perspiration helps dissipate heat produced by  BMR. Some moms experience heat intolerance.

Respiratory system changes Maternal O 2 requirements  in response to  metabolic needs, need to add to uterine muscle and breasts, and fetal demands.  estrogen levels relaxes rib cage allowing  chest expansion Diaphragm may be displaced by 4cm during pregnancy

Respiratory system changes Respiratory Rate– Unchanged or slightly increased Total lung capacity-- Unchanged to slightly decreased Upper respiratory system is more vascularized and sx of nasal & sinus congestion, epistaxis, and ear fullness may occur.

Normal Variations in Vital Signs Blood Volume increases by 1500 ml. Or 40-50% above nonpregnancy levels Heart rate : generally increases by beats/min by the 20 th week gestation and remains to term. Increases in heart volume and cardiac output make splitting S 1 and S 2 and S 3 more audible after 20 wks. Gestation Cardiac Output– Increases by 30 – 50%

Circulatory Changes in Pregnancy

Normal Variations in Vital Signs BP remains the same during the 1 st trimester. In the 2 nd trimester, BP decreases by 5-10 in both systolic and diastolic due normal peripheral vasodilation caused by hormone changes. In the 3 rd trimester, BP returns to 1 st trimester levels. Peripheral vasodilation keeps BP WNL despite the increased blood volume in healthy mom.

Normal Variations in Vital Signs Physiologic anemia – occurs because blood volume increases more rapidly than RBC production Normal Hgb (12-16 g/dl) & Hct (37-47%) If Hgb falls < 11g or Hct < 34%, mom is anemic. RBC mass  by 30-33% by term if an iron supplement is taken.

Normal Variations WBC: Normal non-pregnant = 5-10,000 /mm 3 Normal in pregnancy = 5 – 15,000/mm 3 Predominant WBC’s are Granulocytes (PMN’s or Neutrophils) Normal non-pregnant = 55 – 75% Normal in pregnancy = 60 – 85% Lymphocytes remain basically the same throughout pregnancy.

Inferior Vena Cava Syndrome (IVCS) Caused by the enlarging fetus resting on the mother’s vena cava when in the supine position and this  cardiac return. B/P may drop by 30mm Hg resulting in maternal bradycardia and feeling of dizziness and fainting. Keep mom in a lateral recumbent position or “tilt” for all obstetric procedures (eg.ultrasound, amniocentesis, NST, CST etc.)

Normal Variations Renal Changes: Bladder capacity– Increased to 1500 ml Glomerular Filtration Rate(GFR)-- Increased 30-50% Renal Plasma Flow-Increased 30% Urinary frequency, urgency, & nocturia (without dysuria) are common sx early & late in pg.

Why are bladder infections common in pregnancy? Urinary stasis or stagnation due to anatomical changes in pregnancy.  nutrients including glucose, tend to  urine pH which in turn provides a medium conducive to bacterial growth. ** UTI is one of the most common causes of Preterm Labor and must be treated aggressively when sx occur. Important to teach mom sx of urgency, dysuria,  frequency, flank pain, and contractions.

Fluid Retention—why?? Because of Na + and H 2 O retention, dependent edema is common. Because of pressure of fetus on lower pelvic blood vessels, dependent edema is common. Lateral recumbent position best facilitates kidney perfusion to allow for excretion of excess H2O.

Normal Variations Lab Values: SERUM BUN Decreased (normal: 8-20mg/dl) Creatinine Decreased(normal: 0.6-2mg/dl) Uric Acid Decreased 1 st & 2 nd trimesters (normal: mg/dl) Returns to nml in 3 rd trimester

Normal Variations  Lab Values: URINE  GlucosePresent in urine of 20% of pregnant women (normal: 0-20 mg/dl)  Protein Usually not present, however increased amino acids may spill over from kidneys during pregnancy. Trace to +1 protein are acceptable.

GI System Appetite - Early in pregnancy, many women experience nausea and vomiting beginning around the 4-6th week and ending around the 14th week. Morning sickness is nausea without vomiting. Hcg has been linked as an etiologic factor. Later in pregancy, appetite  secondary to  metabolic needs.

If vomiting persists, or is accompanied by pain, fever or weight loss, medical intervention is indicated. Mouth - ptyalism (excessive salivation)is common in preganancy gums often bleed secondary to  vascularity Stomach & Intestines pyrosis (acid indigestion or heart burn) is caused by  progesterone production which causes the tone and motility of smooth muscles to be , leading to esophageal regurgitaion,  gastric emptying and reverse peristalsis.

Constipation is common secondary to progesterone effects on GI motility and  H2O reabsorption from the colon, displacement of the intestine by the uterus,  activity levels. Hypercholesterolemia - secondary to progesterone is expected and may cause gallstones as well as  emptying time of the gall bladder and thickening of bile in pregnancy.

Endocrine Changes Placenta -- Main source of hormones needed to sustain the pregnancy. Early pregnancy -- the Chorionic Villi secrete Hcg—Human Chorionic Gonadotropin, which prolongs the life of the corpus luteum. HpL -- Human Placental Lactogen influences cellular growth in the fetus and helps prepare breasts for lactation. After 2nd Month of Pregnancy -- The placenta becomes the primary source of Estrogen and Progesterone

Estrogen: promotes enlargement of the genitals, uterus, and breasts— stimulates growth of glandular tissues, ducts, alveoli, and nipples. Progesterone: inhibits spontaneous uterine contractions, develops lobes and alveoli in the breast for lactation,  GI motility

Pituitary Gland Anterior lobe --gonadotropin activity (LH & FSH) is “turned off” by the hormonal activity of the PLACENTA. Prolactin is produced in this lobe but  levels of progesterone and estrogen inhibit by blocking the binding of prolactin to breast tissue. Posterior lobe -- Oxytocin is produced but  levels of Progesterone and Estrogen during pregnancy inhibit its effect on the uterus

Thyroid-- Gland activity and hormone production  during pregnancy. T4  T3  Adrenals--  production of Cortisol  Aldosterone secretion which leads to  Na + and H2O retention Ovaries --generally quiet

IX. Immunological changes-- Placenta acts as interface between mother and fetus thus diminishing maternal response to “antigenic” fetus. Plasma proteins and steroid produced by the placenta alter maternal immune response; predisposes moms to URI. IgG -- only maternal immunoglobulin to cross the placenta. Provides passive immunity to fetus. IgA-- maternal immunoglobulin in colostrum which  GI immunity to breastfed babies

Integumentary Changes  levels of Progesterone and Estrogen cause the release of melanotropin which leads to pigment changes in the skin. Striae gravidarum --stretch marks caused by  connective tissue strength secondary to  adrenal cortisol levels Linea nigra -- vertical abdominal line extending from the symphysis pubis to the top of the fundus. Does not develop in all women.

Linea Nigra & Striae Gravidarum Chloasma of Pregnancy

Chloasma-- “mask of pregnancy” is the blotchy, brownish hyperpigmentation of the skin over the cheeks, nose, and forehead, especially in dark- complexioned, pregnant women. Occurs only in % of pregnant women and usually fades after birth. Darkening of the nipples, areola, axillae, and vulva occurs at the same time. Telangiectasias-- vascular spiders are tiny, star- shaped sl. raised and pulsating end-arterioles secondary to  estrogen levels. Noted on the neck, thorax, face and arms. Occur in 65% of white women & 10 % of black women and disappear after birth.

Sebaceous glands and sweat glands -- Hyperactive during pregnancy which predisposes mom to  pimples/ acne,  perspiration due to  blood supply to the skin Hirsuitism --  growth of hair is a common sx, or a change in the texture of the hair. Some women find hair to be thickest during pregnancy and then experience great hair loss after birth. Usually, self-limiting when hormones return to normal.

Do your best to understand these normal changes in pregnancy so that you can better understand the complications of pregnancy coming up next!